报告人：Dr. Yu Zhong A*STAR, Singapore
时间: 2016/5/3, 10:30-11:30 am
地点: 物理机电航空大楼438会议室
摘要: As one knows, inverse problems in handling waves and fields with only measurement data outside the inspection region are usually ill-posed and nonlinear. This means, when practically solving these problems, numerical solutions are very likely unstable and are difficult to be found (many local minimums far away from the answers). Given the vast potential important applications, such as in nondestructive testing, geoscience survey, and bio-medical imaging, to construct effective inversion solvers to such inverse problems is essential. Trying to tackle them from the perspective of modeling, we have found that there indeed exist proper modelings with which inversions could be carried out with good efficiency. We will discuss two types of methods here, the qualitative type and the optimization type. The former are mainly tailored for targets with dimensions much smaller than the wavelength, including MUSIC-type methods, linear sampling method, while the latter for those with dimensions comparable to wavelength, including various subspace-based optimization methods. In the second part of the talk, computational modelings for composite layered materials will be discussed from two angles: the large-scale aspect and the small-scale aspect. With the large-scale aspect, we consider the composite laminates as uni-axially anisotropic layered media, and fast, yet stable, approaches have been proposed to settle the spectral response to a bounded active source and the spatial response on a rectilinear grid. For the small-scale aspect, such composite laminates are considered as layered media embedded with periodically-arranged cylindrical fibres. Coupling among different layers with different orientations of fibres is tackled with the mode matching technique. Of course, these direct modelings serve to build inversion solvers with such materials.
报告人简介: Dr. Yu Zhong was born in Guangdong, China. He received the B.S. and M.S. degrees in electronic engineering from Zhejiang University, Hangzhou, China, in 2003 and 2006, respectively, and the Ph.D. degree in electrical engineering from the National University of Singapore, Singapore, in 2010. He was a Research Engineer/Fellow with the National University of Singapore, from 2009 to 2013,during which time he was involved in a French-Singaporean MERLION Co-Operative Program. Since 2014, he has been a Scientist with the Institute of High Performance Computing, A*Star, Singapore. He has been invited to the Laboratoire des Signaux et Systèmes, Gif-sur-Yvette, France, as an Invited Scientific Expert once per year from 2010 to 2015. His research interests include numerical methods for inverse scattering problems, waves and fields modeling with complex materials, and nondestructive testing.
